Filter plates are well known. The varied structures, applications, and functions thereof are vast. The basic format—i.e., a configuration comprising substantially flat filtration material incorporated within and held by an outer thermoplastic framework—has been used widely in the construction of, for example, filter presses, normal flow filter disks, electrodeionization devices, multiwell plates, and tangential flow filtration devices.
Under conventional methodologies for manufacturing filter plates, the filtration material is often fixedly incorporated either simultaneously or contemporaneously with the formation of the outer thermoplastic framework. While such methodologies continue to be used with good results, for certain applications, the well-documented post-formation, pre-curing dimensional instabilities of many thermoplastic materials (e.g., shrinkage) can have an unintended influence on the structural integrity of incorporated filtration material. For example, if the filtration material sought to be incorporated is of a type engineered to enable high resolution fluid separations (such as common in biopharmaceutical fluid separations), even a slight structural permutation of a surrounding polymeric framework, even if short lived and temporary, can compromise unacceptably the structural integrity of said filtration material. Certain polymeric raw materials, as the case also with large bulky frame formats, can produce such severe structural contortions during curing that the structural and functional integrity of even a robust filter material is not immune from such influences.
Although technological advances have resulted in the development of polymeric raw materials—such as glass-fiber polymer composites—that retain substantial dimensional stability throughout formation and curing, such innovative materials are often costly. In light of the escalating push in the pharmaceutical industry towards so-called “disposable manufacture”, the costs of such innovative polymeric materials can be prohibitive. They are, in many instances, economically unavailable for use in the making of disposable filtration components and devices.
Need thus exists for an alternative method for making substantially flat filter plates, wherein filtration material can be embedded or otherwise incorporated within a polymeric frame securely, but with less exposure to the dimensional instabilities of the polymeric raw material used to form said frame.